Semiconductor structure in which film including germanium oxide is provided on germanium layer, and method for manufacturing semiconductor structure

Abstract

A semiconductor structure includes: a germanium layer; and a first insulating film that is formed on an upper surface of the germanium layer, primarily contains germanium oxide and a substance having an oxygen potential lower than an oxygen potential of germanium oxide, and has a physical film thickness of 3 nm or less; wherein a half width of frequency to height in a 1 μm square area of the upper surface of the germanium layer is 0.7 nm or less.

The invention claimed is: 
     
       1. A semiconductor structure comprising:
 a germanium layer; and 
 a first insulating film that is formed on an upper surface of the germanium layer, primarily contains germanium oxide and a substance having an oxygen potential lower than an oxygen potential of germanium oxide, and has a physical film thickness of 3 nm or less; 
 wherein a half width of frequency to height in a 1 μm square area of the upper surface of the germanium layer is 0.7 nm or less. 
 
     
     
       2. The semiconductor structure according to  claim 1 , wherein:
 the substance primarily contains at least one element of yttrium oxide, scandium oxide, and aluminum oxide; and 
 an atomic composition ratio of the at least one element of yttrium, scandium, and aluminum to the at least one element and germanium in the first insulating film is 10% or greater and 30% or less. 
 
     
     
       3. The semiconductor structure according to  claim 1 , further comprising:
 a metal layer formed on the first insulating film. 
 
     
     
       4. The semiconductor structure according to  claim 1 , further comprising:
 a second insulating film that is formed on the first insulating film and has a composition different from a composition of the first insulating film; and 
 a metal layer formed on the second insulating film. 
 
     
     
       5. The semiconductor structure according to  claim 1 , wherein
 the half width is 0.5 nm or less. 
 
     
     
       6. A semiconductor structure comprising:
 a germanium layer; and 
 a first insulating film that is formed on an upper surface of the germanium layer, is made of a composite of germanium oxide and an oxide of at least one element of an alkaline-earth element, a rare-earth element, and aluminum, and has a physical film thickness of 3 nm or less; 
 wherein an atomic composition ratio of the at least one element of an alkaline-earth element, a rare-earth element, and aluminum to a total of the at least one element and germanium in the first insulating film is 10% or greater and 30% or less at an interface between the first insulating film and the germanium layer. 
 
     
     
       7. The semiconductor structure according to  claim 6 , wherein
 the at least one element of an alkaline-earth element, a rare-earth element, and aluminum is at least one of yttrium, scandium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. 
 
     
     
       8. The semiconductor structure according to  claim 6 , further comprising:
 a second insulating film that is formed on the first insulating film and has a permittivity greater than a permittivity of silicon oxide; and 
 a gate electrode formed on the second insulating film; 
 wherein the first insulating film is sandwiched between the germanium layer and the second insulating film, and the second insulating film is sandwiched between the first insulating film and the gate electrode. 
 
     
     
       9. The semiconductor structure according to  claim 6 , further comprising:
 a gate electrode formed on the first insulating film without a second insulating film having a permittivity greater than a permittivity of silicon oxide; 
 wherein the first insulating film is sandwiched between the germanium layer and the gate electrode. 
 
     
     
       10. The semiconductor structure according to  claim 6 , wherein
 the first insulating film contains germanium oxynitride. 
 
     
     
       11. The semiconductor structure according to  claim 6 , wherein
 the first insulating film is made of a composite of germanium oxide and at least one of yttrium oxide and scandium oxide. 
 
     
     
       12. The semiconductor structure according to  claim 6 , wherein
 the first insulating film is made of a composite of germanium oxide and yttrium oxide. 
 
     
     
       13. A semiconductor structure comprising:
 a germanium layer; and 
 a first insulating film that is formed on an upper surface of the germanium layer, is made of a composite of germanium oxide and an oxide of at least one element of yttrium and scandium, and has a physical film thickness of 3 nm or less; 
 wherein an atomic composition ratio of the at least one element of yttrium and scandium to a total of the at least one element and germanium in the first insulating film is 6% or greater and 30% or less at an interface between the first insulating film and the germanium layer.